Maybe 2.00$ a kilowatt as an example only, but possibly true for some .
The Generac air cooled HD is not designed for prime continous power,
Any 3600rpm units life is 3000-5000 hrs or 4 months or so, how it is
loaded is important. Im sure Generac has other prime power units, but
the cost. Figure only 1/3rd of the ng burned is converted to
electricity, heat and friction make up th other 2/3 . An 1800 rpm unit
lasts 4 times as long 10-20000 hrs. A 900 rpm Lister over 100000 hrs,
that is prime power. A cheap Honda or Yamaha inverter type with load
dependant rpm could theoreticly last 100,000 hrs. if you kept rpm under
900. The 3000w unit can do that developing only 1-200 watts. For
longest life get a Yamaha or Honda inverter converted to Ng and keep
rpms low. 10,000-12,000 hrs off them is common at medium 50% load , but
at 900 rpm 100000 is possible. Yamaha is heard to have superior
electronics, but I wonder if it isnt really that most people buy the
1600-2000 watts units and just overload them and never consider surge
load, effectively people just abuse them.